Why Do EVs catch fire?
Internal combustion engine cars catch fire due to several varied reasons. It’s a risk we’ve all come to accept in the name of private mobility. Petrol is extremely flammable, which is why the tank that stores it is kept in a safe spot, usually towards the rear of a vehicle. The smallest of sparks can cause fuel to ignite and if that happens to a large enough volume of it, leads to an uncontrollable inferno.
It’s the same story for EVs and despite them not carrying any fuel, are just as susceptible to vehicle fires as ICE ones. An electric vehicle’s motor that receives electricity from the chemical reactions that take place within the battery pack.
Thermal Runaway Is The problem
There are several reasons why an electric vehicle could catch fire but all of them lead back to the battery pack. A puncture, defect or overheating of a pack’s lithium-ion cells could result in a sudden and uncontrollable rise in temperature that eventually leads to a fire.
This is what’s known as thermal runaway and this explosive reaction causes adjacent cells to catch fire as well, which results in a large fireball, which if left unchecked, can engulf an entire vehicle reducing it to an unrecognizable pile of molten metal.
Electric car battery packs consist of between several hundred to several thousand Lithium-ion cells. Like a regular battery, lithium-ion ones consist of an anode (negative) and a cathode (positive) separated by an electrolyte.
When placed in a closed circuit, the battery’s lithium’s outer electron travels across the circuit from the negative to the positive terminal. The lithium-ions, with one less electron, travel from the anode (inside the battery), through the electrolyte and flow towards the battery’s cathode.
What Causes These Fires?
If the balance of these chemicals is not kept in check because of damage, puncture, or unsafe charging, that’s when they begin to overheat and run the risk of catching fire or exploding. An EV doesn’t need to be in a car crash or receive damage to catch on fire. A defect in the battery pack that compromises its overall integrity can be the cause as well.
Besides this, Improper cooling of a battery pack or unbalanced charging can also cause the cells to overheat and catch fire. This is one of the reasons why you may find a perfectly working EV spontaneously “combust” while on the road.
Unlike petrol vehicle fires, EV ones are difficult to extinguish due to the thermal runaway issue mentioned earlier. It can take many hours to put out such a fire. Even then, it’s possible for it to catch fire again hours or days later.
That is why EV battery packs need to be manufactured properly and under the most stringent quality control regulations. It’s also important that the onboard system ensures that charging is done properly and that the cooling system keeps these cells operating at an optimum temperature.
